I realize this is pretty old, but I’ve recently done a bit of research on this as well. Disqus doesn’t seem to support it.

The apostrophe HTML mark-up you’ve written is not an apostrophe. It’s a prime. In typography, primes are either ‘ or ” and are used to denote feet or inches, respectively. Unfortunately, those are the keys manufacturers chose to include on keyboards rather than real apostrophes or quotations.